An introductory text-book of logic - Mellone, Sydney - Rare Books at ...

DEFINITION. 177
said (An. Post., ii. 10) that a nominal definition gives
the current meaning of a term, as when thunder is said
"
to be "a noise in the clouds," or a house
a building in
which people live." A verbal or nominal definition need
not have even the implication of real existence added
it may be of things afterwards shown to be impossible
e.g.,
"
perpetual motion
"
or
"
squaring the circle." But
sometimes this verbal definition has added to it the
postulate of real existence or validity, as in the examples
given above (cp. also An. Post, i. i). A real definition
is the statement of what is essential to the fact in ques
tion as a matter of science. In fact, Aristotle s dis
tinction practically coincides with that of definition as
the beginning and as the end of knowledge ; in this
sense we must retain it, but we need not distinguish
the two types of definition as "nominal" and "real."
Modern writers usually express the distinction in
terms similar to those of Aristotle,
"
"
nominal
"
and
"
real but ; scarcely two of them explain it alike. If
we retain this expression of it, we must remember that
all definitions define the meanings of terms or names,
and so may be called
"
"
nominal
: while on the other
hand, some definitions evidently have a direct reference
to a real thing, others, again, evidently aim first of all
at fixing the meaning of a term, and have only an in
direct reference to reality. Even this distinction does
not go deep. For as Professor Sidgwick has observed,
we never define a term for its own sake merely, but in
order to understand the things to which it refers. A
mere word, apart from the things for which it stands,
has no interest for us.
" The truth is, as most readers
of Plato know, only
it is a truth difficult to retain and
apply, that what we gain by discussing a definition is
often but slightly represented by the superior fitness of
M